Liero-AI is a side-view fighting game with an enormous number of weapons. No other game that I know of lets you use Iridium satellites as weapons.

Enigma is seemingly a clone of an old DOS game called Oxyd. Oxyd was a very smart puzzle game which endeared itself to me by not using the same moving parts for every puzzle; there was some basic thing different about the game engine for just about every puzzle. This game deviates from that somewhat, but it's still got that great Oxyd gameplay (you toss a black sphere across the screen with your mouse; it's really fun).

Trackballs is a Marble Madness-ish game. I couldn't get it to run, but it looks fun.

Mojotron is suspiciously similar to Robotron and Llamatron. Sadly, is less bizarre and frenetic than Llamatron. Contains fake Engrish on title screen!

Iter Vehemens ad Necem is a graphical roguelike with a realistic damage system ("Realistic damage system" == "There's gonna be dismemberment"; I think Penny Arcade once did a strip on this topic) and a properly roguelike obsession with fruit. I recommend it, and I usually don't recommend non-ASCII roguelikes.